Re: archive logs

From: Vishal Gupta <vishal_at_vishalgupta.com>
Date: Thu, 26 May 2016 10:52:54 +0100
Message-ID: <25C08015-DDAB-4789-A7E1-1458E2A10DD7_at_vishalgupta.com>

There are many data warehouse systems which can produce lots of data in a very short span of time. We have combination of OLTP+DW 8-node RAC db on Exadata, which had 30GB of redo log. It use to produce 700GB of archive logs within an hour at its peak.

Regards,
Vishal Gupta

From: <oracle-l-bounce_at_freelists.org> on behalf of Mladen Gogala Reply-To: <gogala.mladen_at_gmail.com>
Date: Tuesday, 24 May 2016 at 05:19
To: <oracle-l_at_freelists.org>
Subject: Re: archive logs       

Hi Jack,
 The largest redo log that I have ever seen was 20GB in size. In my opinion that doesn't make much sense because the transport through the WAN is extremely problematic and it would take forever to apply just a single log. Generally speaking, I don't think that log sizes over 1GB are warranted. Maybe 2GB, if the WAN connection is very fast and reliable and log application is fast. I would be very hard pressed to imagine a system that would have 20GB of net change in less than 1 hour, as a regular occurrence.  Regards    

 On 05/23/2016 11:56 PM, Jack van Zanen wrote:        

Hi      

This probably provides the info required, but on a very busy period there may be more frequent log switches      

so when you setup this report      

"ARCHIVE_LAG_TARGET =600" for instance forces a log switch every 10 minutes but you could have one every 5 or 2 or 1 minutes if system is very busy.  

So unlike SQL Server where it is fixed by a schedule, within oracle it is handled by the size of the online redo log files, number of changes happening, setting of ARCHIVE_LAG_TARGET and probably a few more things.          

Jack        

Jack van Zanen  

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On Sat, May 21, 2016 at 4:51 AM, Chris Taylor <christopherdtaylor1994_at_gmail.com> wrote:      

ARCHIVE_LAG_TARGET I meant....       

Chris         

On Fri, May 20, 2016 at 1:50 PM, Chris Taylor <christopherdtaylor1994_at_gmail.com> wrote:      

lag_archive_target for the win.      

Chris                                  

-- 
Mladen Gogala
Oracle DBA
Tel: (347) 321-1217
 




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Received on Thu May 26 2016 - 11:52:54 CEST